U.S. patent number 5,213,644 [Application Number 07/672,455] was granted by the patent office on 1993-05-25 for method of and apparatus for producing moisture block stranded conductor.
This patent grant is currently assigned to Southwire Company. Invention is credited to Steven R. Campbell, Hai T. Lam, Donald R. Phillips, Clinton E. Watkins.
United States Patent |
5,213,644 |
Phillips , et al. |
May 25, 1993 |
Method of and apparatus for producing moisture block stranded
conductor
Abstract
A method of and an apparatus for applying a moisture block
compound to a stranded electrical conductor using a double twist
buncher apparatus are disclosed. An oil, such as drawing oil, is
applied to the outer layer of wires to prevent "rolling" of the
moisture block compound to the exterior of the stranded conductor.
An improved applicator is also disclosed for applying the moisture
block compound to the core of the stranded conductor in a coating
having a precisely controlled thickness.
Inventors: |
Phillips; Donald R. (Delta,
AL), Lam; Hai T. (Chamblee, GA), Watkins; Clinton E.
(Villa Rica, GA), Campbell; Steven R. (Carrollton, GA) |
Assignee: |
Southwire Company (Carrollton,
GA)
|
Family
ID: |
24698616 |
Appl.
No.: |
07/672,455 |
Filed: |
March 20, 1991 |
Current U.S.
Class: |
156/51; 118/420;
174/23C; 427/118; 427/434.7 |
Current CPC
Class: |
H01B
13/0285 (20130101); H01B 13/323 (20130101) |
Current International
Class: |
H01B
13/32 (20060101); H01B 13/02 (20060101); H01B
013/32 () |
Field of
Search: |
;156/51 ;264/174
;57/7,296,6,295,297 ;174/23R,23C,12SC ;118/420 ;427/118,434.7
;29/461,527.2 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Simmons; David A.
Assistant Examiner: Osele; Mark A.
Attorney, Agent or Firm: Wallis, Jr.; James W. Tate; Stanley
L. Myers, Jr.; George C.
Claims
What is claimed is:
1. A wire stranding apparatus including a double twist buncher
apparatus for fabricating a moisture blocked stranded conductor
having a core and a first plurality of wires surrounding the core,
said conductor having inner interstices between the core and said
first plurality of wires, comprising:
means for delivering the core and the plurality of wires to the
double twist buncher;
means for applying a coating of moisture block compound to the
core;
means for twisting said first plurality of wires about the coated
core so as to fill the inner interstices with moisture block
compound and form a moisture blocked stranded conductor;
means arranged upstream of said twisting means for applying oil
only to said first plurality of wires surrounding the core; and
means for taking-up the stranded conductor.
2. The apparatus of claim 1, wherein said oil applying means
comprises an inlet block having eyelets through which the core and
said plurality of wires pass and a supply of oil connected to the
eyelets through which said first plurality of wires pass.
3. The apparatus of claim 1, wherein said core comprises only one
round wire and said first plurality of wires comprises round
wires.
4. The apparatus of claim 1, wherein said core comprises a second
plurality of wires and said first plurality of wires comprises
round wires.
5. The apparatus of claim 6, wherein the apparatus is adapted for
handling wires in which at least some of the wires of the core are
generally trapezoidally shaped in cross-section.
6. The apparatus of claim 5, wherein the apparatus is adapted for
handling wires in which said second plurality of wires are round
wires and said first plurality of round wires includes wires of
different diameters.
7. A wire stranding apparatus including a double twist buncher
apparatus for fabricating a moisture blocked stranded conductor
having a core and a first plurality of wires surrounding the core,
said conductor having inner interstices between the core and said
first plurality of wires, comprising:
means for delivering the core and the plurality of wires to the
double twist buncher;
means for applying a coating of moisture block compound to the
core;
means for twisting said first plurality of wires about the coated
core so as to fill the inner interstices with moisture block
compound and form a moisture blocked stranded conductor;
means arranged upstream of said twisting means for applying oil
only to said first plurality of wires surrounding the core so as to
prevent rolling of said moisture block compound out from the inner
interstices; and
means for taking-up the stranded conductor.
8. A method of fabricating a moisture blocked stranded conductor
having a core and a first plurality of wires surrounding the core,
said conductor having inner interstices between the core and said
first plurality of wires, comprising the steps of:
delivering said core and said first plurality of wires to a buncher
apparatus;
applying a coating of moisture block compound to the core;
applying oil only to said first plurality of wires;
twisting the oiled first plurality of wires about the coated core
so as to fill the inner interstices between the core and the first
plurality of wires with moisture block compound and form a moisture
blocked stranded cable.
9. The method of claim 8, including the step of taking-up the
stranded cable, said twisting step being performed upstream of the
taking-up step and downstream of the step of applying moisture
block compound to the core.
10. The method of claim 8, wherein said oil is a wire drawing
oil.
11. The method of claim 8, wherein said oil supplying step is
performed upstream of the moisture block applying step.
12. The method of claim 8, wherein said core comprises a second
plurality of wires.
Description
FIELD OF THE INVENTION
The present invention relates to a method of and an apparatus for
producing a moisture block stranded electrical conductor on a
double twist buncher. More particularly, the present invention
relates to an improved method of and apparatus for applying a
moisture block compound to the interstices between the core wire
and the outer layer(s) of wire that are twisted over the core wire
in a double twist buncher apparatus.
DESCRIPTION OF THE PRIOR ART
Stranded electrical conductors fabricated with a plurality of round
wires made of an electrically conductive metal, such as copper or
aluminum, are well known in the art, as are methods and apparatus
for making such stranded conductors. Typically, stranded conductors
are fabricated by stranding or bunching together a plurality of
round wires in concentric layers about a core wire. As used herein,
the term "core wire" includes a single core wire as well as a
stranded conductor used as a core wire for a second or subsequent
layer of wires.
Generally speaking, there are three conventional types of apparatus
for making stranded electrical conductors having a plurality of
round wires which are twisted about the longitudinal conductor
axis. One known apparatus known as a rigid frame strander employs a
rotating pay-out system. In a rigid frame strander, a plurality of
spools of wire are mounted on a rotatable laying head through which
a core wire passes. As the laying head is rotated, the wires from
the plurality of spools are helically wrapped or twisted about the
advancing core wire and passed through a closing die to form a
stranded conductor which is collected on a take-up reel.
A second type of apparatus employs a rotating take-up reel in which
the take-up reel is rotated about two axes, namely, the reel axis
for take-up purposes and the conductor axis to provide a twist to
the conductor. In this second type of apparatus, a plurality of
wires are advanced in substantially side-by-side relation from a
plurality of spools or stem packs mounted on a stationary platform.
The wires are guided to a stationary lay plate through the axis of
which one of the wires passes as a core wire and the remaining
wires are concentrically spaced about the core wire. The wires are
passed from the lay plate to a closing die and thence to take-up
reel which twists the stranded conductor.
The third known type of apparatus for making stranded cable is a
buncher, e.g., a double twist buncher, in which the wires are
advanced from stationary spools in side-by-side relation through a
stationary twist plate and to a closing die. In the buncher,
however, neither the pay-out system nor the take-up system rotates
but a twist is applied to the wires of the stranded conductor by a
rotating bow mechanism located between the closing die and the
take-up reel. Advantageously, the double-twist buncher is a more
efficient and economical apparatus than either the rigid frame
strander with a rotating pay-out system or the apparatus with a
rotating take-up reel because the double twist buncher provides two
twists in the stranded conductor for each revolution of the
rotating bow. Thus, for a given speed of rotation, production rate
of a buncher is almost twice the production rate of the machines
with a rotating pay-out or take-up system. Moreover, the double
twist buncher is a more compact system because the pay-out spools
and the take-up reel, need not be mounted for rotation as they must
in the other types of stranding apparatus.
When round wires of the same diameter are used to form a stranded
conductor, e.g., a seven stranded conductor, six wires are normally
stranded concentrically about a single core wire. For stranded
conductors with a greater number of strands, successive concentric
layers typically include six strands more than the number of
strands in the preceding layer. Thus, a stranded conductor with a
core wire and two concentric wire layers typically comprises
nineteen (19) wires, i.e., the core wire, six wires in the first
layer and twelve wires in the second layer. A stranded conductor
with a core wire and three concentric wire layers comprises
thirty-seven (37) wires, i.e, the core wire, six wires in the first
layer, twelve in the second layer and eighteen in the third layer.
Of course, stranded conductors may be formed with a greater or
lesser number of wires in each successive layer, the important
parameter being the total or cross-sectional area of the wires.
One disadvantage of stranded conductors, particularly those
intended for underground use, is the tendency for water or moisture
to flow or seep longitudinally through the stranded cable in the
interstices between the core wire and the surrounding wires in the
first concentric layer, or between the wires of the first and
second concentric layers and so on. Heretofore, numerous attempts
have been made to prevent the flow of water or moisture
longitudinally through the stranded conductor using various
methods, apparatus and moisture block compounds. One such method is
disclosed in U.S. Pat. No. 4,874,442 assigned to the assignee of
the present invention. In that method, a plurality of wires
including a core wire are passed through a cone die into which a
moisture block compound is fed by a pump via a connecting pipe. A
first layer of outer wires is loosely stranded by a rotating
pay-out system over a core wire and coated with a predetermined
volume of moisture block compound. This loosely stranded conductor
is then passed through a closing block with another plurality of
wires mounted on another rotating pay-out system to form a second
layer of outer wires. The conductor exiting the closing block is a
finished stranded conductor which has been treated with a volume of
moisture block compound sufficient to fill all the interstitial
spaces in the stranded conductor.
Another method of producing a moisture block stranded conductor is
disclosed in U.S. Pat. No. 2,427,507 in which a blocking compound
is applied to a center strand which passes through an opening in
the center of a rotating pay-out head. The pay-out head twists a
plurality of wires about the core such that the sealing compound
fills the interstices between the core wire and the twisted
wires.
U.S. Pat. Nos. 3,889,455 and 4,129,466 disclose other methods of
and apparatus for applying a moisture block to a stranded conductor
by passing the wires through a tank or chamber containing the
blocking material. These patents disclose the use of the moisture
block methods and apparatus with stranders using either a rotating
pay-out system or a rotating take-up system.
When applying a moisture blocking compound to a stranded conductor
with one or more concentric layers of wires, the amount of moisture
blocking compound must be carefully controlled to prevent excess
moisture blocking compound from seeping through the outer layer of
wires and onto the outer surfaces of the stranded conductor. By the
proper sizing of the die through which the moisture block-coated
core wire or stranded conductor is passed and by controlling the
application pressure of the compound, the amount of applied
compound may be precisely regulated. One problem that can occur,
especially in the case of stranded conductor made on a double twist
buncher, results from the inherent additional twist induced in the
individual wires as they enter the buncher apparatus. Such
additional twist causes each wire to rotate approximately
one-quarter turn at the final twisting point of the machine thereby
causing the moisture block compound to be carried or "rolled" to
the outer interstices of the stranded conductor. Such rolling
action depletes the controlled amount of moisture block compound in
the interstices between the core wire and the layer of wires
surrounding the core wire and undesirably results in the outer
surfaces of the wire layer becoming coated with moisture block
compound.
SUMMARY OF THE INVENTION
In view of the foregoing limitations and disadvantages of the prior
art methods and apparatus for moisture blocking stranded conductors
made with round wire, especially those made on a buncher-type
apparatus, it should be apparent that there still exists a need in
the art for a method of producing a moisture blocked stranded cable
in which the moisture block compound is precisely controlled and
confined to the inner interstices between the core wire and the
surrounding layer of wires. It is, therefore, a primary object of
this invention to fulfill that need by providing a method of and an
improved buncher apparatus for applying a moisture block compound
to a stranded conductor made from a plurality of round wires
wherein a thin coating of oil is applied to the wires of the outer
layers prior to contacting the core wires to prevent them from
"rolling" the moisture block compound on the core wire from the
inner interstices to the outer surfaces of the stranded
conductor.
Advantageously, in a double twist buncher apparatus the oil is
applied to each outer wire as it passes through its respective
eyelet in the inlet block of the buncher apparatus. In the case of
stranded conductors having more than one concentric layer of wires,
oil is applied only to the outermost concentric layer and not to
the core (which comprises a center wire and one or more concentric
layers of wires). The moisture block compound is applied to a
cleaned or degreased core wire so as to ensure adhesion of the
blocking compound to the core wire. The compound-coated core wire
is then passed through a die sized to achieve a precisely
controlled amount of blocking compound surrounding the core. Since
the layer of outer wires has an oil coating, the moisture blocking
compound does not adhere to the outer wires and is not "rolled" to
the outer surfaces of the stranded conductor. As the outer layer of
wires is twisted over the core wire, there is sufficient mechanical
pressure between the core wire and the outer layer of wires to
effect a satisfactory moisture block seal, i.e., in the manner of a
gasket seal. Thus, the lack of adhesion between the moisture block
compound and the outer layer of wires does not adversely affect the
moisture blocking of the stranded conductor.
One oil that has been successfully used in the inventive method
with aluminum wires is Cindol 4683 wire drawing oil made by E. F.
Houghton Co. of Valley Forge, Pa., however, those skilled in the
art will appreciate that there are many equivalent oils that may be
used.
The invention also comprises an improved applicator head and die
holder for application of the moisture block compound to the core
wire (or core wires in the case of a seven strand core wire). The
applicator head comprises a small cylindrical chamber into which a
moisture block compound is introduced from an extruder at a
pressure slightly greater than atmospheric pressure. A split die
with a central bore is mounted in one end of the chamber and is
held in place by a U-shaped threaded die cap. The central bore of
the split die has a tightly toleranced diameter so as to closely
control the thickness of moisture block compound on the core wire
passing through it. The back or upstream end of the chamber is
provided with a removable plug with a bore through which the core
wire passes into the chamber. In the case of a core made up of
seven strands, for example, the plug functions as a closing die for
the outer layer of six strands.
Relief holes or grooves are provided around the periphery of the
removable plug so that the machine operator can control the flow of
moisture block compound to prevent underfilling of the stranded
conductor as well as to prevent excessive overfilling that might
cause an excess of moisture block compound to extrude through the
split die and around the core wire.
With the foregoing and other objects, advantages and features of
the invention that will become hereinafter apparent, the nature of
the invention may be more clearly understood by reference to the
following detailed description of the invention, the appended
claims and to the several views illustrated in the attached
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic side elevation view of a double twist buncher
incorporating the moisture block apparatus of the invention for
making a seven strand moisture blocked conductor;
FIG. 2 is a schematic top plan view of the buncher apparatus of
FIG. 1;
FIG. 3 is a side elevation view in cross-section of the applicator
head of the present invention;
FIG. 4 is an end view of the applicator head of FIG. 3 taken along
line 4--4 of FIG. 3;
FIG. 5 is an end view of the die cap and applicator taken along
line 5--5 of FIG. 3;
FIG. 6 is a cross-section of a moisture blocked seven strand
conductor; and
FIG. 7 is a cross-section of a moisture blocked nineteen strand
conductor.
DETAILED DESCRIPTION OF THE INVENTION
Referring now in detail to the drawings, there is schematically
illustrated in FIGS. 1 and 2 a buncher apparatus designated
generally by reference numeral 10 which is operated in accordance
with the method of the invention. The apparatus 10 may be a
conventional buncher known as a double twist buncher made by Ceeco
of Concord, Ontario, Canada, but modified to incorporate the
present invention. As shown in FIGS. 1 and 2 a plurality of round
wires 12, 13, 14, 15, 16, 17, 18 comprising seven equal diameter
wires are withdrawn from a respective spool or reel (not shown) and
pass over a respective pulley or sheave 20 from which they are
guided in a generally horizontal direction to an inlet block 22 of
the buncher apparatus 10. The wires 12-18 may be formed of any
conductive metal, especially aluminum or copper or alloys thereof.
Inlet block 22 is provided with a plurality of eyelets (not shown)
through which a respective one of the wires 12-18 is guided into a
common horizontal plane. The wire 15 is the core wire and the wires
12-14 and 16-18 will be twisted by the buncher apparatus 10 about
the core wire 15 to form an outer concentric layer of wires
surrounding core wire 15 as shown in cross-section in FIG. 6.
An oil supply reservoir 24 is connected via pipes 26 to the inlet
block 2 which is provided with internal passages (not shown)
intersecting the eyelets through which the wires 12-14 and 16-18
travel. No oil is supplied to the eyelet through which the core
wire 15 passes (FIG. 2). The supply of oil is sufficient to lightly
coat the surfaces of each wire 12-14, 16-18 for a purpose to be
hereinafter described.
Downstream of the inlet block 22, the core wire 15 passes into an
applicator head 28 to which a moisture block compound is supplied
by an extruder 30 via a heated pipe 32. Head 28 applies a
controlled amount of moisture block compound to the outer
circumferential surface of core wire 15 as a coating having a
uniform and precisely controlled thickness. The coated core wire
15' exits the head 28 and passes through a central opening (not
shown) in stationary twist plate 34.
The oiled wires 12'-14' and 16'-18' travel outside of and past the
applicator head 28 where they are guided through the twist plate 34
by rollers (not shown) mounted in the twist plate 34 at 60.degree.
spacings about the twist plate axis along which coated core wire
15' travels. Downstream of the twist plate 34 there is arranged a
closing die 36 where the oiled wires 12'-14' and 16'-18' are
converged onto the outer surface of moisture block-coated core wire
15'. The oiled wires are twisted over the coated core wire 15' to
form a moisture blocked stranded conductor 38 (FIG. 6) by a
conventional take-up system 40 comprising a rotating bow 42 which
rotates about the axis of conductor 38 to twist the same and a
take-up reel 44 which rotates only about a horizontal axis
transverse to the longitudinal axis of the buncher apparatus 10 to
take-up the stranded conductor.
When the oiled wires 12'-14' and 16'-18' reach the first twisting
point at or adjacent the closing die 36, each wire is wound around
the coated core wire 15' to form a stranded conductor.
Subsequently, a second twist is imparted to the entire stranded
conductor which causes each wire to rotate about its own axis
approximately a one-quarter turn. This wire rotation is inherent in
the double twist buncher apparatus. The oil on the wires 12'-14'
and 16'-18' prevent the moisture block compound on coated wire 15'
from adhering to the surfaces of those wires and thus prevents
"rolling" of the compound to the outside of the stranded conductor
38. Thus, as shown in FIG. 6, the inner interstices between the
core wire and the outer concentric layer of wires are completely
filled with moisture block compound 39 and no compound is "rolled"
or otherwise caused to flow to the outer surfaces of the stranded
conductor.
Referring now to FIGS. 3-5 there is shown in cross-section one
embodiment of the applicator head 28 for applying the moisture
block compound to the core wire of a stranded conductor having
seven wires. Head 28 comprises a cylindrical chamber body 50 with a
stepped bore 52, 53 extending therethrough. A tapered split die 54
is inserted in a tapered portion 56 of the downstream end of the
bore 52 and is urged into tight sealing relation with the tapered
portion 56 by a die cap 58. Die cap 58 has an internal thread 60
which is threadably engaged with the external thread 62 on the
downstream end of the body 50. Die 54 has a central bore 55 which
is closely toleranced to precisely control the diameter and amount
of moisture block compound applied to the core wire.
As best seen in FIG. 5, the die cap 58 has a generally U-shaped
form with an axial bore 64 intersected by a wide radial slot 66 so
that the die cap can be assembled to and removed from the thread 60
on the body 50 when a core wire extends axially through the body.
The die cap 58 is also provided with a pair of parallel flat
surfaces 68, 70 to facilitate threading the die cap onto and off of
the threaded end of the body with a wrench or other tool. The die
54 is preferably formed as a split die, i.e., made in two identical
parts 54a, 54b so that the die 54 can be removed and replaced when
a core wire extends along the axis of the body 50. Replacement of a
die 54 may be necessary when the core wire is strung through the
applicator, for example, when it is necessary to change the
diameter of the bore 55 to adjust the thickness of the moisture
block compound on the core wire.
The bore 53 in the upstream end of the body 50 has an annular
shoulder 72 against which a closing plug 74 abuts. Closing plug 74
has a central bore 76 through which the core wire passes and is
held in position by locking screws 78 threaded through the wall of
body 50. If desired, the closing plug 74 may also be fabricated in
two identical pieces similar to the split die 54. A plurality of
longitudinally extending grooves 80 are machined in the wall of
body 50 defined by bore 53. Grooves 80 extend from the open
upstream end of the body 50 past the plug 74 and shoulder 72 and
terminate in the chamber 82 defined by the bores 52, 53 and the
confronting end surfaces of the die 54 and the plug 74. It would
also be possible to provide grooves or channels in the outer
periphery of the closing plug 74.
Moisture block compound is introduced into the chamber 82 from
extruder 30 via heated pipe 32 (FIG. 1) which is threadably
connected to a threaded bore 84 in the wall of body 50. In
operation, a core wire travels through the bore 76 in plug 74, the
chamber 82 and the central bore 55 in split die 54 from right to
left as viewed in FIG. 3. Moisture block compound is forced through
bore 84 under a pressure slightly greater than atmospheric into the
chamber 82 to fill it. As the core wire passes through the chamber
82, moisture block compound adheres to the cleaned and degreased
surface of the core wire and the bore 55 in die 54 precisely
controls the thickness of the compound coating on the core wire as
it passes through the die 54.
The moisture block compound in chamber 82 is also forced through
grooves 80 and out the upstream ends of the grooves. By visually
observing the amount and rate of compound flowing from the grooves,
the machine operator can regulate the flow and pressure of the
extruder to prevent overfill and underfill conditions. If compound
is observed flowing out of the grooves 80, an overfill or
overpressure condition exists which could cause an excess amount of
compound to flow out of the split die around the core wire. On the
other hand, if compound is observed flowing from the grooves 80
inwardly toward the chamber 82, an underfill or underpressure
condition exists which could result in voids in the moisture block
coating on the core wire and an insufficient amount of compound on
the core wire to fill all the inner interstices. The possibility of
voids in the moisture block coating is not only the result of an
underfill or underpressure condition in the applicator. Voids in
the coating can also result from the natural tunneling effect of a
non-rotating wire passing through the moisture block compound at a
relatively high rate of speed. It is, therefore, desirable to
maintain a slight overfill condition of the applicator to
substantially eliminate the possibility of voids in the moisture
block coating.
It is also possible to manufacture moisture blocked stranded
electrical conductors with a greater number of wires than the seven
wire conductor described above in connection with FIGS. 1, 2 and 6.
For example, a stranded conductor with nineteen wires as shown in
cross-section in FIG. 7 designated with reference numeral 100 can
also be made in a double twist buncher of the type shown in FIGS. 1
and 2. In such case, the core comprises the seven wires 102
corresponding to the seven wires shown in FIG. 6 and the outer
layer of wires comprises the twelve wires 104 surrounding the core
102. Moisture block compound 106 fills all the inner interstices
between the wires 102 and between the wire 102 and the wires 104.
The seven wires 102 pass through inlet block eyelets which are not
connected to an oil supply. The twelve wires 104 pass through oiled
eyelets in the inlet block. Wires 102 are guided into the upstream
end of the applicator head by a conical closing die which replaces
the plug 74. Die 54 is replaced by a split die having a bore with a
diameter greater than the diameter of bore 55. The seven strand
core of wires 102 exits the die coated with moisture blocking
compound having a precisely controlled diameter. The oiled wires
104 pass through a twist plate similar to plate 34 and are
converged onto the moisture block-coated core in a closing die in
the same manner as shown in FIGS. 1 and 2.
The invention also contemplates constructions of stranded
electrical conductors other than those shown in FIGS. 6 and 7. For
example, stranded conductors having a compacted core formed six or
seven shaped wires (e.g., generally trapezoidal in cross-section)
concentrically disposed about a round core wire and an outer layer
of round core wires arranged about the compacted core may be made
according to the method of the invention using the apparatus of the
invention. Likewise, combination stranded conductors having round
wires of differing cross-sections, such as a Unilay construction
made according to ASTM B786-88 are also contemplated by the
invention. It is also possible to use the double twist buncher to
fabricate a fully compacted stranded conductor with moisture
blocking compound in all inner interstices of the conductor. Such
conductors are made of a plurality of shaped wires having a
trapezoidal cross-section arranged about a round core wire. In the
case of a fully compacted conductor, it is not necessary to oil the
outermost layer of shaped wires since the shaped wires are
prevented by their shape from rotating at the final twisting point
of the buncher.
It is also within the scope of the present invention to supply oil
to the outermost layer of round wires at a point downstream of the
inlet block. Those skilled in the art will appreciate that so long
as the outer layer of wires are oiled prior to entry into the
closing die 36 of the buncher apparatus of FIGS. 1 and 2 "rolling"
of the moisture block compound can be prevented and that objective
of the invention can be accomplished.
Although certain presently preferred embodiments of the invention
have been described herein, it will be apparent to those skilled in
the art to which the invention pertains that variations and
modifications of the described embodiment may be made without
departing from the spirit and scope of the invention. Accordingly,
it is intended that the invention be limited only to the extent
required by the appended claims and the applicable rules of
law.
* * * * *